Does anyone know how to increase the height of matchbox-keyboard keys or the keyboard itself?

I'm trying to make matchbox-keyboard look like the opera browser built-in keyboard as much as possible, by playing around with the .matchbox/keyboard.xml for my n800.
The height of the buttons is almost half the opera buttons. Niether the README, the man-page nor the usage info have height/size info.

The source code references MBKeyboardImage which makes me wonder, but I'd rather not modify/recompile if theres some easy hidden little switch somewhere.